Process and contrivance for producing hollow bodies by casting



Aug. 21, 1934. s. SCHWIETZKE 1,971,279

PROCESS AND CONTRIVANCE FOR PRODUCING HOLLOW BODJES BY CASTING- Filed Oct. 1:. 1952 m 7/ f J fll //7 van for:

Patented Au 21, 1934 mocsss "m 1,971,219 CONTRIVANCE roa mo DUCING HOLLOW. BODIES BY CASTING Giinther Schwietzke, Dusseldorf, Germany Application October 13, 1932. Serial No. 637,855 I In Germany October 14, 1931 The tubes hitherto produced by casting have a relatively great inner-width and a slight thickness. The employed casting machines .with either horizontal, slanting, or vertical axes of rotation are mostly closed completely at the one end and at the other end they are provided with a terminal ring. The latter forms a ringshaped interior projection of the turn-mould and serves for fixing the length of the tubes to be produced. This ring has an inward radial extension a little greater than the wall-thickness of the tube to be produced, in order to prevent an escape of the introduced liquid cast-material.

This terminal ring constitutes at the same time the entrance to the mould through which, in hori- 'zontal or slanting casting machines, the casting contrivance (a casting tube, a casting channel) is inserted. The casting contrivance, owing to its unavoidable lining with incombustible ma terial and for reasons of stability, assumes a considerable diameter. Hitherto, in the production of the wide tubes, the relatively large opening of the terminal ring left suiiicient room for introducing and drawing out the casting contrivance. The minimum diameter of the casting contrivance, however, fixes the smallest possible opening of the terminal ring. This, and also the fact that hitherto the cast-material is filled into the tum-mould not further than up to. the inner h edge of the terminal ring, fixes the minimal inner width that can be given to the produced tubes. Considering the advantageous qualities and results of the casting process, it is desirable to be able to produce in this manner also hollow bodies of a smaller inner width, in particular, rolls with narrow bore. This is rendered possible by the invention which principally consists in the fact that, when introducing the cast-material into the mould, owing to a special cooling contriv- 40-31106, at the place for fixing the desired length of the hollow body to be produced, the liquid cast material solidiiicates quickly and forms a solid ring-shaped damming projection. This cast damming projection substitutes or completes the hitherto used terminal ring of the tum-mould and, in the same way as the terminal ring, it prevents the cast-material still liquid inside the mould from escaping to the entrance side. Considering that the damming projection only needs to grow according'to the growing level of the liquid, it is sufiicient if the finishing rest of the introduced cast-material is used for raising the damming projection up to its full height. This possibility is also utilized, in horizontal or slanting turn-moulds with introduced casting contrlvance, for casting thick-walled hollow bodies with an inner width snpaller than the diameter of the entrance hole. The cast material is introduced intothe turning mould in such a quantity that, when drawing out the casting contrivance, 0" r the liquid cast-material that follows up the casting'contrivance forms a hollow space having an inner span smaller than that of the introducing Opening. At the introducing opening or the mould the liquid cast-material flowing from the casting contrivance is caused, by strongcooling, to solidificate quickly, so as to form by itself a damming projection that prevents an escape of the liquid cast-material inside of themould.

The details 0! the process according to theinvention may be seen from the accompanying drawing, in which Fig. 1 is a section through the mold showing v conditions at the beginning of the pouring operation. v v

Fig. 2 is a section taken on the line 'A-B of Fig. 1. a

Fig. 3 is a section similar to Fig. 1 but showing conditions at the end of the pouring operation. The turn-mould rotating on its longitudinal axis placed in a somewhat slanting position (Figure 1) consists in a cylindric box (a) with an in-- sertion (al) of sand, loam or the like, produced by throwing, which determines the exterior diameter of the roll to be produced. At the one (lower) end the turning mould (M1) is closed by a solid disc (a2), at the other (upper) end a tubular terminal ring (1)) is inserted. This determines with its inner face (bl) the useful length of the roll to be produced. Its bore forms the opening for introducing and drawing out the casting channel (c) and is adapted in its diameter to the cross-cut of the casting channel, small enough to let the latter pass through without touching (Fig. 2). The casting channel lined inside with incombustible material is movable in longitudinal direction in relation to the turnmould (M1), for which purpose either this mould or the casting channel as well as the container of the cast-material attached to the back, or both parts, are arranged on the basis in the known manner by means of suitable moving contrivances with regulatable velocity, movable towards another.

The turn-mould (a-.al) is cooled, which is indicated by the water cover (a3). This cooling at the same time also extends to the tubular terminal ring (b).

For the purpose of casting, the casting channel (0) with its front outlet (01) is introduced nearly liq up to the end disc (all into the turn-mould (a-a1), and this is set into rotation. Then the cast-material is introduced through the channel into the mould, the quantity of current being regulated exactly, and at the same time the channel is drawn back with a certain velocity. The introduced quantities and the velocity of the drawing out of the casting channel are to be such that the cast-material rises behind the outlet (cl) of the channel in inward radial direction up to or over its ground (c2) and forms a thickwalled hollow body (d) having the required bore,

- the diameter of which is smaller than the inner span of the tubular terminal ring (b) (Fig. 1). When the outlet (01) of the casting channel reaches the terminal ring and passes through some outwards, the cast-material, after filling the inner mould space limited by the terminal ring, runs over the front space (121) of the terminal 4 ring into its inner casing space (b2). The flowing in. is now continued for a certain length either in the same quantity as before, or by shutting oil the inflow or, somewhat throttled, by a quicker drawing out of the channel, so that a short appendage ((11) to the roll (d) in the terminal ring is formed (Fig. 3). This appendage is brought to solidification by quick cooling through the water cooling (a3) and the relatively great heat capacity and good heat conductivity of the massive terminal ring, quickly enough to let the appendage act as a damming projection for preventing an escape of any of the liquid cast-material of the cast hollow body, so that the inner width of the latter does not get widened at its end part, and that it receives over its whole length a cylindric here After taking the produced roll (d) out of the tum-mould, its appendage gets removed.

The tubular terminal ring (12) may also just be placed before the turn mould (H1), without reaching into it, and the required quicl: cooL- ing of the appendage (d1) i'ormed therein will be effected by the properly sized length and thickness of the terminal ring, as well as bytheuse of, building material of great heat conductivity, or also by an air current cooling.

I claim: a

l. The method of casting hollow metallic bodies in a centrifugal mould having a charging opening, consisting in charging molten metal through the charging opening into the rotating mould until the fluid metal forms a tubular mass having a bore of less diameter than the diameter of the charging opening, and chilling the molten metal adiacent the charging opening to form a solidifled dam to prevent outflow oi the molten metal through the discharge opening.

2. The method of casting hollow metallic bodies in a centrifugal mould having a charging opening or less diameter than the interior diameter of the mould, consisting in charging molten metal through the charging opening into the rotating mould until the fluid metal flows into the restricted opening and the fluid metal forms a tubular mass in the mould and extending into the discharge opening with the tubular mass having a bore extending through the same of less diameter than the diameter of the charging opening, and chilling the tubular mass of molten metal in the charging opening to form therein a solidified dam to prevent outflow of the fluid metal through said opening.

3. A mould for centrifugal casting comprising a tubular main part, a metallic plug at an end of the main part provided with an axial charging opening of less diameter than'the interior diameter of the main part of the mould, means for charging molten metal through the discharging opening of the plug into the main part of the mould until the fluid metal overflows said main part into the restricted charging opening of the plug during the rotation of the mould, and means for chilling the plug to solidify the molten metal in the charging opening to form therein a dam to prevent the outflow through said opening of the molten metal contained in the main part 01' the mould during the rotation of the mould.

4. A mould for centrifugal casting comprising a tubular body part provided with a refractory lining extending from one end thereof part way through the same, a metal plug seated in the other end of the tubular body part and abutting the refractory lining, said plug having one axial charging opening or less diameter than the interior diameter of the refractory-lined part of the tubular body part, means for delivering molten metal through the charging opening of the plug into the refractory-lined part of the tubular body part until the metal overflows the refractory lined part into the restricted discharge opening during the rotation of the mould, and means for chilling the plug to solidify the molt-en metal in the discharge opening to form a dam therein to prevent outflow through said opening of the molten metal contained in the lined body part during rotation of the same.

GUNTKER so. 

